Do Adductor Canal Blocks Provide Additional Analgesic Benefit to Periarticular Injection Alone for Primary Total Knee Arthroplasty?

BACKGROUND: The added benefit of preoperative, anesthesiologist-performed adductor canal blocks (ACBs) to a modern pain management regimen in total knee arthroplasty (TKA), including multimodal analgesia and periarticular injection (PAI), remains controversial. This study compared opioid consumption and postoperative pain in TKA patients receiving ACB + PAI vs PAI alone.

METHODS: This was a single-surgeon retrospective review of patients who underwent unilateral primary TKA over a 2-year period. During year 1, no patients received ACB. During year 2, all patients received ACB. Morphine milligram equivalents, visual analog scale (VAS), and summed pain intensity difference values were compared between both groups over the first 24 hours postoperatively. The final sample included 188 patients: 104 with ACB + PAI and 84 with PAI only.

RESULTS: The mean total morphine milligram equivalents of opioids administered was lower in the ACB + PAI group (31.6 [range: 0-177] vs 42.5 [range: 0-103.5]; P < .01). The ACB + PAI group had lower mean VAS scores (3.1 [range: 0-7.2] vs 4.0 [range: 1.2-6.5]; P < .001). Median maximum VAS pain scores were also lower in the ACB + PAI group (7.0 [interquartile range: 6.0-8.5] vs 8.0 [interquartile range: 7.0-9.0]; P < .001). Similarly, the mean summed pain intensity differ value was lower in the ACB + PAI group (40 [range: 0-118] vs 54 [range: 9-121]; P < .001). These findings remained significant after adjusting for age, sex, body mass index, and American Society of Anesthesiologists class.

CONCLUSIONS: The addition of an ACB to PAI was associated with lower postoperative pain values and reduced opioid consumption compared to PAI alone in the first 24 hours postoperatively.